Problems with in-tree host libraries (gmp, ppl, etc)

[Paolo Bonzini]

> If the C and the C++ interface of GMP have been installed in the same
> places,
> specifying --with-libgmp-prefix[=DIR] is enough.
> 
> If you think that being able to use a non-installed GMP build tree is
> important, we can add an option to that effect.

Yes, that would help.  mpfr is using --with-gmp-build as the option name.

Paolo